really awesome that cutting edge crypto is being used by our elected officials & their aides to avoid public records laws!
For any classified material officials can use their SIPRNET/JWICS emails, for which suspicious access is much more closely monitored, of course.
Not many security people in the world would sign on to that position.
Do you mean to suggest that Gmail is more secure than government classified networks?
Signal's authors may be more technically competent than a government security officer, but Signal can be coerced into releasing an update that surreptitiously changes the behavior of the application whereas well-protected NSA officers are (theoretically) more immune.
Clearly, I'd rather Clinton use GApps than run her own email server. But for security, her worst option was the official servers.